Publications

• Identification and characterization of catabolic para-nitrophenol 4-monooxygenase and para-benzoquinone reductase from Pseudomonas sp. strain WBC-3.

  Zhang J.J., Liu H., Xiao Y., Zhang X.E., Zhou N.Y.

  Pseudomonas sp. strain WBC-3 utilizes para-nitrophenol (PNP) as a sole source of carbon, nitrogen, and energy. In order to identify the genes involved in this utilization, we cloned and sequenced a 12.7-kb fragment containing a conserved region of NAD(P)H:quinone oxidoreductase genes. Of the produ ... >> More

  Pseudomonas sp. strain WBC-3 utilizes para-nitrophenol (PNP) as a sole source of carbon, nitrogen, and energy. In order to identify the genes involved in this utilization, we cloned and sequenced a 12.7-kb fragment containing a conserved region of NAD(P)H:quinone oxidoreductase genes. Of the products of the 13 open reading frames deduced from this fragment, PnpA shares 24% identity to the large component of a 3-hydroxyphenylacetate hydroxylase from Pseudomonas putida U and PnpB is 58% identical to an NAD(P)H:quinone oxidoreductase from Escherichia coli. Both PnpA and PnpB were purified to homogeneity as His-tagged proteins, and they were considered to be a monomer and a dimer, respectively, as determined by gel filtration. PnpA is a flavin adenine dinucleotide-dependent single-component PNP 4-monooxygenase that converts PNP to para-benzoquinone in the presence of NADPH. PnpB is a flavin mononucleotide-and NADPH-dependent p-benzoquinone reductase that catalyzes the reduction of p-benzoquinone to hydroquinone. PnpB could enhance PnpA activity, and genetic analyses indicated that both pnpA and pnpB play essential roles in PNP mineralization in strain WBC-3. Furthermore, the pnpCDEF gene cluster next to pnpAB shares significant similarities with and has the same organization as a gene cluster responsible for hydroquinone degradation (hapCDEF) in Pseudomonas fluorescens ACB (M. J. Moonen, N. M. Kamerbeek, A. H. Westphal, S. A. Boeren, D. B. Janssen, M. W. Fraaije, and W. J. van Berkel, J. Bacteriol. 190:5190-5198, 2008), suggesting that the genes involved in PNP degradation are physically linked. << Less

  J. Bacteriol. 191:2703-2710(2009) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• Novel pathway for conversion of chlorohydroxyquinol to maleylacetate in Burkholderia cepacia AC1100.

  Zaborina O., Daubaras D.L., Zago A., Xun L., Saido K., Klem T., Nikolic D., Chakrabarty A.M.

  Burkholderia cepacia AC1100 metabolizes 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) via formation of 5-chlorohydroxyquinol (5-CHQ), hydroxyquinol (HQ), maleylacetate, and beta-oxoadipate. The step(s) leading to the dechlorination of 5-CHQ to HQ has remained unidentified. We demonstrate that a dech ... >> More

  Burkholderia cepacia AC1100 metabolizes 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) via formation of 5-chlorohydroxyquinol (5-CHQ), hydroxyquinol (HQ), maleylacetate, and beta-oxoadipate. The step(s) leading to the dechlorination of 5-CHQ to HQ has remained unidentified. We demonstrate that a dechlorinating enzyme, TftG, catalyzes the conversion of 5-CHQ to hydroxybenzoquinone, which is then reduced to HQ by a hydroxybenzoquinone reductase (HBQ reductase). HQ is subsequently converted to maleylacetate by hydroxyquinol 1,2-dioxygenase (HQDO). All three enzymes were purified. We demonstrate specific product formation by colorimetric assay and mass spectrometry when 5-CHQ is treated successively with the three enzymes: TftG, TftG plus HBQ reductase, and TftG plus HBQ reductase plus HQDO. This study delineates the complete enzymatic pathway for the degradation of 5-CHQ to maleylacetate. << Less

  J Bacteriol 180:4667-4675(1998) [PubMed] [EuropePMC]

• Fe-superoxide dismutase and 2-hydroxy-1,4-benzoquinone reductase preclude the auto-oxidation step in 4-aminophenol metabolism by Burkholderia sp. strain AK-5.

  Takenaka S., Koshiya J., Okugawa S., Takata A., Murakami S., Aoki K.

  Burkholderia sp. strain AK-5 converts 4-aminophenol to maleylacetic acid via 1,2,4-trihydroxybenzene, which is unstable in vitro and non-enzymatically auto-oxidized to 2-hydroxy-1,4-benzoquinone. Crude extract of strain AK-5 retarded the auto-oxidation and reduced the substrate analogue, 2,6-dimet ... >> More

  Burkholderia sp. strain AK-5 converts 4-aminophenol to maleylacetic acid via 1,2,4-trihydroxybenzene, which is unstable in vitro and non-enzymatically auto-oxidized to 2-hydroxy-1,4-benzoquinone. Crude extract of strain AK-5 retarded the auto-oxidation and reduced the substrate analogue, 2,6-dimethoxy-1,4-benzoquinone, in the presence of NADH. The two enzymes responsible were purified to homogeneity. The deduced amino acid sequence of the enzyme that inhibited the auto-oxidation showed a high level of identity to sequences of iron-containing superoxide dismutases (Fe-SODs) and contained a conserved metal-ion-binding site; the purified enzyme showed superoxide dismutase activity and contained 1 mol of Fe per mol of enzyme, identifying it as Fe-SOD. Among three type SODs tested, Fe-SOD purified here inhibited the auto-oxidation most efficiently. The other purified enzyme showed a broad substrate specificity toward benzoquinones, including 2-hydroxy-1,4-benzoquinone, converting them to the corresponding 1,4-benzenediols; the enzyme was identified as 2-hydroxy-1,4-benzoquinone reductase. The deduced amino acid sequence did not show a high level of identity to that of benzoquinone reductases from bacteria and fungi that degrade chlorinated phenols or nitrophenols. The indirect role of Fe-SOD in 1,2,4-trihydroxybenzene metabolism is probably to scavenge and detoxify reactive species that promote the auto-oxidation of 1,2,4-trihydroxybenzene in vivo. The direct role of benzoquinone reductase would be to convert the auto-oxidation product back to 1,2,4-trihydroxybenzene. These two enzymes together with 1,2,4-trihydroxybenzene 1,2-dioxygenase convert 1,2,4-trihydroxybenzene to maleylacetic acid. << Less

  Biodegradation 22:1-11(2011) [PubMed] [EuropePMC]